Method of fabricating metal mask and metal mask

ABSTRACT

A method of fabricating a metal mask includes receiving a conductive substrate with a first surface, a second surface opposite to the first surface, a third surface connecting the first and second surfaces, and a fourth surface opposite to the third surface and connecting the first and second surfaces. The method further includes forming trenches in a direction from the first surface to the second surface and protrusions in the conductive substrate. The trenches and the protrusions are alternately arranged. The method further includes filling the trenches with an insulation material covering a first area of the protrusions, forming a metal layer on the conductive substrate overlying a second area different from the first area of the protrusions, removing the insulation material, and removing the conductive substrate. The metal layer becomes a metal mask with a three-dimensional structure including strip-shaped structures.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Taiwan Application Ser. No.110131682, filed Aug. 26, 2021, which is herein incorporated byreference in its entirety.

BACKGROUND Field of Invention

The present disclosure relates to a method of fabricating a metal maskand the metal mask. More particularly, the present disclosure relates toa method of fabricating a three-dimensional metal mask and thethree-dimensional metal mask.

Description of Related Art

The display device has been used in a variety of applications. Thedisplay device includes various electrical components and wiresconnecting the electrical components. For example, the wire can transmitsignal to a thin film transistor (TFT) and apply a voltage to anelectrode in the TFT. In response to the market demand, the screen tobody ratio of the display device is being increased.

Therefore, the narrow bezel display device has been developed and becomepopular in the market. The peripheral area of the narrow bezel displaydevice is effectively utilized to form the wires for electricalconnection between the electrical components disposed on different sidesof the substrate.

SUMMARY

An aspect of the present disclosure provides a method of fabricating ametal mask. The method of fabricating the metal mask includes receivinga conductive substrate with a first surface, a second surface oppositeto the first surface, a third surface connecting the first and secondsurfaces, and a fourth surface opposite to the third surface andconnecting the first and second surfaces. The method of fabricating themetal mask further includes forming trenches in a direction from thefirst surface to the second surface and protrusions in the conductivesubstrate. The trenches and the protrusions are alternately arranged.The method of fabricating the metal mask further includes filling thetrenches with an insulation material covering a first area of theprotrusions, forming a metal layer on the conductive substrate overlyinga second area different from the first area of the protrusions, removingthe insulation material, and removing the conductive substrate. Themetal layer becomes a metal mask with a three-dimensional structureincluding strip-shaped structures.

An aspect of the present disclosure provides a metal mask. The metalmask includes a first board portion and strip-shaped structuresconnected to the first board portion. Two adjacent strip-shapedstructures of the strip-shaped structures are spaced apart from eachother. The strip-shaped structures comprise a first section having afirst thickness and a second section having a second thickness. Thesecond thickness is substantially the same as the first thickness. Thesecond section connects the first board portion and the first section. Afirst angle is formed by the first section and the second section.

It is to be understood that both the foregoing general description andthe following detailed description are by examples, and are intended toprovide further explanation of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 to FIG. 5 are views of various intermediate stages of fabricatinga metal mask according to some embodiments of the present disclosure.

FIG. 6 is a cross-sectional view of a metal mask taken along line A-Ashown in FIG. 5 according to some embodiments of the present disclosure.

FIG. 7 to FIG. 9 are views of various intermediate stages of applying ametal mask shown in FIG. 5 according to some embodiments of the presentdisclosure.

FIG. 10 to FIG. 12 are views of various intermediate stages offabricating a metal mask according to some other embodiments of thepresent disclosure.

FIG. 13 is a cross-sectional of a metal mask taken along line B-B shownin FIG. 12 according to some other embodiments of the presentdisclosure.

FIG. 14 to FIG. 17 are views of various intermediate stages of applyinga metal mask shown in FIG. 12 according to some other embodiments of thepresent disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the present embodiments of thedisclosure, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or like parts.

The following disclosure provides many different embodiments, orexamples, for implementing different features of the disclosure. Forillustration clarity, many details of practice are explained in thefollowing descriptions. However, it should be understood that thesedetails of practice do not intend to limit the present disclosure. Thatis, these details of practice are not necessary in parts of embodimentsof the present disclosure. For example, the formation of a first featureover or on a second feature in the description that follows may includeembodiments in which the first and second features are formed in directcontact, and may also include embodiments in which additional featuresmay be formed between the first and second features, such that the firstand second features may not be in direct contact.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

The use of ordinals such as first, second and third does not necessarilyimply a ranked sense of order, but rather may only distinguish betweenmultiple instances of an act or structure. It will be understood that,although the terms first, second, third etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms are only used to distinguish oneelement, component, region, layer or section from another element,component, region, layer or section. Thus, a first element, component,region, layer or section discussed below could be termed a secondelement, component, region, layer or section without departing from theteachings of the present disclosure.

In some embodiments, the terms “about” and “substantially” can refer toa percentage of the values as interpreted by those skilled in relevantart(s) in light of the teachings herein. The terms “about” and“substantially” can indicate a value of a given quantity that varieswithin an acceptable deviation of the value. These values are merelyexamples and are not intended to be limiting.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

In the fabrication of a display device, particularly a narrow bezeldisplay device, a wire formed at an edge of a substrate in the displaydevice by using a conductive through hole, lithography techniques, oretching techniques can electrically connect various electricalcomponents separately disposed on two opposite sides of a substrate.However, manufacturing the conductive through hole in the substrate maynot be fully established in the fabrication of the display device, and alithography process and/or an etching process may complicate thefabrication of the display device. As a result, the fabricationdifficulty and cost may be increased.

The present disclosure provides a metal mask with a three-dimensionalstructure and a method of fabricating thereof. The metal mask with thethree-dimensional structure can be used to form wires at the edge of thesubstrate and between the electrical components which are separatelydisposed on two opposite sides of the substrate.

Referring to FIG. 1 to FIG. 5 , FIG. 1 to FIG. 5 are views of variousintermediate stages of fabricating the metal mask according to someembodiments of the present disclosure. Various operations of embodimentsare provided herein. The order in which some or all of the operationsare described should not be construed to imply that these operations arenecessarily order dependent. Alternative ordering will be appreciatedhaving the benefit of this description. Additional operations can beprovided before, during, and/or after these operations in FIG. 1 to FIG.5 , and may be briefly described herein. Further, it will be understoodthat not all operations are necessarily present in each embodimentprovided herein. Also, it will be understood that not all operations arenecessary in some embodiments.

FIG. 1 illustrates step S10 of receiving a conductive substrate 100. Theconductive substrate 100 can include a first surface S1 (e.g., parallelto the xy plane), a second surface S2 opposite to the first surface S1,a third surface S3 connecting the first surface S1 and the secondsurface S2 (e.g., parallel to the xz plane), and a fourth surface S4opposite to the third surface S3 and connecting the first surface S1 andthe second surface S2. The conductive substrate 100 includes anysuitable conductive materials, such as metal. In some embodiments, theconductive substrate 100 may include Cu, Ni, Fe, Co, Sn, Cr, Ti, Al,other suitable metal, an alloy of the above-mentioned metal, or acombination thereof. For example, the conductive substrate 100 caninclude Ni. In some other embodiments, the conductive substrate 100 canbe a stainless steel.

A length L1 (e.g., a dimension along the x axis) and a width W1 (e.g., adimension along the y axis) of the conductive substrate 100 can bemanipulated based on product designs and process conditions. In someembodiments, the length L1 and the width W1 of the conductive substrate100 can be determined in step S10. In some other embodiments, the lengthL1 and the width W1 of the conductive substrate 100 can be determined inthe subsequent step, for example in step S12 in the following context.

FIG. 2 illustrates step S12 of forming multiple trenches 200 in adirection from the first surface S1 to the second surface S2 (e.g.,downward along the z axis) and multiples protrusions 102 in theconductive substrate100. In some embodiments, the conductive substrate100 can be machined to recess the first surface S1 of the conductivesubstrate 100, thereby forming the trenches 200 in the conductivesubstrate 100. In an embodiment as shown in FIG. 2 , the trenches 200extends through the third surface S3 and the fourth surface S4, implyingthat a length of each trench 200 along the y axis can be substantiallythe same as a distance between the third surface S3 and the fourthsurface S4. That is, the length of each trench 200 along the y axis canbe substantially the same as the width W1 of the conductive substrate100.

The conductive substrate can include the protrusions 102 and a base 104after the trenches are formed. In some embodiments, each trench 200 canbe located two adjacent protrusions 102. In other words, each trench 200and each protrusion 102 are alternately arranged. In some embodiments,the protrusions 102 can protrude from the base 104 and extend upward(e.g., upward along the z axis).

FIG. 3 illustrates step S14 of filling the trenches 200 (see FIG. 2 )with a first insulation material 300. In some embodiments, the firstinsulation material 300 can cover a first area of the protrusions 102,as shown in FIG. 3 . Specifically, the first insulation material 300filled into the trenches 200 (see FIG. 2 ) may contact a sidewall of theprotrusions 102 within the trenches 200 (see FIG. 2 ) and an uppersurface of the base within the trenches 200 (see FIG. 2 ). In someembodiments, the first insulation material 300 can also cover an outersidewall and a portion of surface of the conductive substrate 100 (e.g.,the second surface S2). With the first insulation material 300, apredetermined area can be exposed. In some embodiments, different formthe first area of the protrusions 102 covered by the first insulationmaterial 300, a second area of the protrusions 102 can be exposed. Ametal layer may later be formed on the exposed surface (i.e. the secondarea) in the following steps (will be discussed later). In an embodimentas shown in FIG. 3 , the first surface S1, the third surface S3 and thefourth surface S4 may be the predetermined area, so the first surfaceS1, the third surface S3 and the fourth surface S4 may be exposedwithout coverage of the first insulation material 300.

FIG. 4 illustrates step S16 of forming a metal layer 400 on the exposedsurface of the conductive substrate 100. In some embodiments, the metallayer 400 can overlie the second area of the protrusions 102 which isnot covered by the first insulation material 300 (see FIG. 3 ). In anembodiment as shown in FIG. 4 , the metal layer 400 can overlie on thesurface exposed in a structure of FIG. 3 , for example the first surfaceS1, the third surface S3 and the fourth surface S4.

In a further description, the metal layer 400 may include multiplestrip-shaped structures 402 and a board portion 404. The strip-shapedstructures 402 can be a portion of the metal layer 400 overlying theprotrusions 102. In an example, the strip-shaped structures 402 can beformed on and cover the first surface S1, the third surface S3 and thefourth surface S4 exposed on the protrusions 102 (see FIG. 3 ). Theboard portion 404 can be a portion of the metal layer 400 formed on thebase 104. In an example, the board portion 404 can be formed on andcover the third surface S3 and the fourth surface S4 exposed on the base104 (see FIG. 3 ).

In some embodiments, a method for forming the metal layer 400 on theconductive substrate 100 can include electrochemically depositing amaterial of the metal layer 400 on the conductive substrate 100. Thematerial of the metal layer 400 may include Cu, Ni, Fe, Co, Sn, Cr, Ti,Al, other suitable metal, an alloy of the above-mentioned metal, or acombination thereof. For example, the material of the metal layer 400can include Ni. During a process of the electrochemical deposition, theconductive substrate 100 shown in FIG. 3 can be provided with anelectric current (e.g., connected to an external power supply). In thiscase, once an electrolyte touches the exposed surface in the conductivesubstrate 100, an ion (e.g., the material of the metal layer 400 in anionic state) in the electrolyte may be reduced (that is, undergo areduction reaction) to form the metal layer 400 on the exposed surfacein the conductive substrate 100. Consequently, the exposed surfacearranged by the first insulation material 300 on the conductivesubstrate 100 can determine a profile or design of the metal layer 400.

The metal layer 400 can include a thickness T1 between about 20micrometers (μm) and about 300 μm. In some embodiments, the thickness T1can be between about 20 μm and about 150 μm. If the thickness T1 is lessthan 20 μm, the process may become challenging. For example, in thesubsequent process of peeling (e.g., removing the conductive substrate100 and keeping the metal layer 400), the metal layer 400 withundesirably thin thickness may require precise operation and gentlehandling to ensure an intact profile of the metal layer 400. If thethickness T1 is greater than 300 μm, no significant advantages can beobtained. In some embodiments, for example, a shadow effect may occurwhen the thickness T1 exceeds 300 μm. In some embodiments, the thicknessT1 of the metal layer 400 can be a uniform thickness.

In some embodiments, a surface treatment can be performed on theconductive substrate 100 before the metal layer 400 is formed thereon.For example, in some embodiments in which a material included in theconductive substrate 100 is the same as a material included in the metallayer 400, performing the surface treatment on the conductive substrate100 before depositing the metal layer 400 on the treated conductivesubstrate 100 can facilitate a separation between the conductivesubstrate 100 and the metal layer 400 in the subsequent process ofpeeling (e.g., removing the conductive substrate 100 and keeping themetal layer 400). In some embodiments, the surface treatment can includeforming an oxide layer on the conductive substrate 100. In general, thesurface treatment may not have influence on a formation of the metallayer 400.

FIG. 5 illustrates step S18 of removing the first insulation material300, and further removing the conductive substrate 100 such that themetal layer 400 can become a metal mask 400 with a three-dimensionalstructure. As shown in FIG. 5 , the metal mask 400 with thethree-dimensional structure can have the strip-shaped structures 402,the board portion 404 and the thickness T1.

The metal mask 400 shown in FIG. 5 is further described. The boardportion 404 of the metal mask 400 may include a first board portion404-1 and a second board portion 404-2. In some embodiments, the firstboard portion 404-1 and the second board portion 404-2 can be parallelto each other. Two adjacent strip-shaped structures 402 of thestrip-shaped structures 402 can be spaced apart from each other.Further, the strip-shaped structures 402 can connect the first boardportion 404-1 and the second board portion 404-2. The strip-shapedstructures 402 may include a first section 402-1, a second section 402-2and a third section 402-3. In some embodiments, the first section 402-1may be positioned above the second section 402-2 and the third section402-3, and meanwhile connect the second section 402-2 and the thirdsection 402-3. In addition, the second section 402-2 may connect thefirst board portion 404-1 and the first section 402-1, and the thirdsection 402-3 may connect the second board portion 404-2 and the firstsection 402-1. In some embodiments, the second section 402-2 and thethird section 402-3 can be parallel to each other.

In some embodiments, if the thickness T1 of the metal layer 400 canoriginally be a uniform thickness as described in FIG. 4 , the metalmask 400 in FIG. 5 turned from the metal layer 400 can keep having theuniform thickness T1. Therefore, a thickness of the first section 402-1,a thickness of the second section 402-2 and a thickness of the thirdsection 402-3 can be substantially the same. In other words, the firstsection 402-1, the second section 402-2 and the third section 402-3 canall have the thickness T1.

Continuing in FIG. 5 and referring to FIG. 6 at the same time, FIG. 6illustrates a cross-sectional view of the metal mask 400 taken alongline A-A shown in FIG. 5 according to some embodiments of the presentdisclosure. In some embodiments as shown in FIG. 6 , a cross-sectionalstructure of the metal mask 400 may be similar to anupside-down-U-shaped structure. A first angle 81 is formed by the firstsection 402-1 and the second section 402-2, and a second angle 82 isformed by the first section 402-1 and the third section 402-3. Asdiscussed previously in FIG. 3 , an arrangement of the first insulationmaterial 300 on the conductive substrate 100 can therefore determine aprofile or design of the metal mask 400.

In some embodiments, a length D1 of the first section 402-1 cansubstantially be the same as the width W1 of the conductive substrate100 in FIG. 1 . In some other embodiments, a distance D2 between aninner surface of the second section 402-2 and an inner surface of thethird section 402-3 can substantially be the same as the width W1 of theconductive substrate 100 in FIG. 1 when the second section 402-2 and thethird 403-2 are parallel to each other. In some other embodiments, adistance D3 between an inner surface of the first board portion 404-1and an inner surface of the second board portion 404-2 can substantiallybe the same as the width W1 of the conductive substrate 100 in FIG. 1when the second section 402-2 and the third 403-2 are parallel to eachother as well as the first board portion 404-1 and the second boardportion 404-2 are parallel to each other.

Referring to FIG. 7 to FIG. 9 , FIG. 7 to FIG. 9 are views of variousintermediate stages of applying the metal mask 400 shown in FIG. 5according to some embodiments of the present disclosure. For example,the metal mask 400 is used to form wires at the edge of a slab-shapedsubstrate. Various operations of embodiments are provided herein. Theorder in which some or all of the operations are described should not beconstrued to imply that these operations are necessarily orderdependent. Alternative ordering will be appreciated having the benefitof this description. Additional operations can be provided before,during, and/or after these operations in FIG. 7 to FIG. 9 , and may bebriefly described herein. Further, it will be understood that not alloperations are necessarily present in each embodiment provided herein.Also, it will be understood that not all operations are necessary insome embodiments.

FIG. 7 illustrates step A10 of receiving a slab-shaped substrate 700 anddisposing the metal mask 400 at the edge of the slab-shaped substrate700. In detail, the board portion 404 of the metal mask 400 can directlycontact a fifth surface S5 and a sixth surface S6 of the slab-shapedsubstrate 700. The fifth surface S5 and the sixth surface S6 areopposite to each other and may be parallel to the xy plane. Thestrip-shaped structures 402 of the metal mask 400 can directly contactthe fifth surface S5, the sixth surface S6 and a seventh surface S7. Theseventh surface S7 connects the fifth surface S5 and the sixth surfaceS6, and may be parallel to the yz plane.

The profile of the metal mask 400 is designed to be consistent with aprofile of the slab-shaped substrate 700, thereby allowing the metalmask 400 to fit an edge area of the slab-shaped substrate 700. In someembodiments, a width W2 of the slab-shaped substrate 700 cansubstantially be the same as the length D1 of the first section 402-1 ofthe strip-shaped structures 402 (see FIG. 6 ).

FIG. 8 illustrates step A12 of forming a metal material 800 on anexposed portion of the slab-shaped substrate 700 without the metal mask400 covered. Specifically, the metal material 800 can be formed betweeneach of the strip-shaped structures 402. A thickness of the metalmaterial 800 may be less than a thickness of the metal mask 400 (e.g.the thickness T1 shown in FIG. 5 ). In some embodiments, a mask (notillustrated here) may be used to cover some other portions of theslab-shaped substrate 700 to avoid the metal material 800 from appearingthereon. In some embodiments, the metal material 800 can be formed by asputtering process, an evaporation process, or any suitable process. Itis noted that, in an actual operation, the metal material 800 may beformed not only on the exposed portion of the slab-shaped substrate 700but also on the metal mask 400. For clarity, FIG. 8 is simplified byomitting to illustrate a portion of the metal material 800 on the metalmask 400.

Due to a low coefficient of heat expansion, the metal mask 400 may notbe changed with temperature in terms of structure such as expansion orcontraction of volume during a process of forming the metal material 800by the sputtering process, the evaporation process or the like.Therefore, the metal mask 400 can remain original arrangement, therebyensuring process stability of forming the metal material 800 and furtherincreasing reliability of metal wires formed later (e.g., metal wires900 in below FIG. 9 ).

FIG. 9 illustrates step A14 of removing the metal mask 400 such that theremaining metal material 800 can become the metal wires 900 at the edgeof the slab-shaped substrate 700. The metal wires 900 can extend on thefifth surface S5, the sixth surface S6 and the seventh surface S7continuously. The metal wires 900 can electrically connect variouselectrical components (not illustrated here) separately disposed on thefifth surface S5 and sixth surface S6. With the metal mask 400, themetal wires 900 can be formed at the edge of the slab-shaped substrate700 in a convenient way.

Referring to FIG. 10 to FIG. 12 , FIG. 10 to FIG. 12 are views ofvarious intermediate stages of fabricating a metal mask with anotherstructure according to some other embodiments of the present disclosure.Operations for fabricating the metal mask with another structure can besimilar to the operations for fabricating the metal mask 400 asabove-mentioned description. For example, step S24 discussed later inFIG. 10 can be similar to step S14 discussed in FIG. 3 , step S26discussed later in FIG. 11 can be similar to step S16 discussed in FIG.4 , and step S28 discussed later in FIG. 12 can be similar to step S18discussed in FIG. 5 . Further, step S10 discussed in FIG. 1 and step S12discussed in FIG. 2 can be directly implemented in the operations forfabricating the metal mask with another structure. Therefore, no furtherdiscussions are elaborated for step S10 and step S12.

Additional operations can be provided before, during, and/or after theseoperations in FIG. 10 to FIG. 12 , and may be briefly described herein.Further, it will be understood that not all operations are necessarilypresent in each embodiment provided herein. Also, it will be understoodthat not all operations are necessary in some embodiments.

FIG. 10 illustrates step S24 of additionally forming a second insulationmaterial 1000 on the fourth surface S4 base on the structure in FIG. 3 .Therefore, the first surface S1 and the third surface S3 may be thepredetermined area to be exposed without coverage of the firstinsulation material 300 and the second insulation material 1000. In someembodiments, a material of the second insulation material 1000 cansubstantially identical to a material of the first insulation material300.

FIG. 11 illustrates step S26 of forming a metal layer 1100 on an exposedsurface of the conductive substrate 100. In other words, the metal layer1100 can partially overlie the protrusions 102 which are not covered bythe first insulation material 300 and the second insulation material1000 (see FIG. 10 ). In an embodiment as shown in FIG. 11 , the metallayer 1100 can overlie on the exposed surface in a structure of FIG. 11, for example the first surface S1 and the third surface S3.

In a further description, the metal layer 1100 may include multiplestrip-shaped structures 1102 and a board portion 1104. The strip-shapedstructures 1102 can be a portion of the metal layer 1100 formed on theprotrusions 102. In an example, the strip-shaped structures 1102 can beformed on and cover the first surface S1 and the third surface S3exposed on the protrusions 102 (see FIG. 10 ). The board portion 1104can be a portion of the metal layer 1100 formed on the base 104. In anexample, the board portion 1104 can be formed on and cover the thirdsurface S3 exposed on the base 104 (see FIG. 10 ).

In some embodiments, a method for forming the metal layer 1100 on theconductive substrate 100 can include electrochemically depositing amaterial of the metal layer 1100 on the conductive substrate 100. Thematerial of the metal layer 1100 may include Cu, Ni, Fe, Co, Sn, Cr, Ti,Al, other suitable metal, an alloy of the above-mentioned metal, or acombination thereof. For example, the material of the metal layer 1100can include Ni. During a process of the electrochemical deposition, theconductive substrate 100 shown in FIG. 10 can be provided with anelectric current (e.g., connected to an external power supply). In thiscase, once an electrolyte touches the exposed surface in the conductivesubstrate 100, an ion (e.g., the material of the metal layer 1100 in anionic state) in the electrolyte may be reduced (that is, undergo areduction reaction) to form the metal layer 1100 on the exposed surfacein the conductive substrate 100. Consequently, the exposed surfacearranged by the first insulation material 300 and the second insulationmaterial 1000 on the conductive substrate 100 can determine a profile ordesign of the metal layer 1100.

The metal layer 1100 can include a thickness T2 between about 20 μm andabout 300 μm. In some embodiments, the thickness T2 can be between about20 μm and about 150 μm. If the thickness T2 is less than 20 μm, theprocess may become challenging. For example, in the subsequent processof peeling (e.g., removing the conductive substrate 100 and keeping themetal layer 1100), the metal layer 1100 with undesirably thin thicknessmay require more precise operation and gentle handling to ensure anintact profile of the metal layer 1100. If the thickness T2 is greaterthan 300 μm, no significant advantages can be obtained. In someembodiments, for example, a shadow effect may occur when the thicknessT2 exceeds 300 μm. In some embodiments, the thickness T2 of the metallayer 1100 can be a uniform thickness.

Similarly, a surface treatment can be performed on the conductivesubstrate 100 before the metal layer 1100 is formed thereon. Operationsfor performing the surface treatment are as discussed previously in FIG.4 , and thus no further description is elaborated herein.

FIG. 12 illustrates step S28 of removing the first insulation material300 and the second insulation material 1000, and further removing theconductive substrate 100 such that the metal layer 1100 can become ametal mask 1100 with a three-dimensional structure. As shown in FIG. 12, the metal mask 1100 with the three-dimensional structure can have thestrip-shaped structures 1102, the board portion 1104 and the thicknessT2.

The metal mask 1100 shown in FIG. 12 is further described. Two adjacentstrip-shaped structures 1102 of the strip-shaped structures 1102 can bespaced apart from each other. Further, the strip-shaped structures 1102can connect the board portion 1104. The strip-shaped structures 1102 mayinclude a first section 1102-1 and a second section 1102-2. In someembodiments, the first section 1102-1 may be positioned above the secondsection 1102-2, and meanwhile connected to the second section 1102-2. Insome embodiments, the metal mask 110 can be corresponded to the metalmask 400 shown in FIG. 5 . For example, the first section 1102-1 can becorresponded to the first section 402-1 shown in FIG. 5 , the secondsection 1102-2 can be corresponded to the second section 402-2 shown inFIG. 5 , and the board portion 1104 can be corresponded to the firstboard portion 404-1.

In some embodiments, if the thickness T2 of the metal layer 1100 canoriginally be a uniform thickness as described in FIG. 11 , the metalmask 1100 in FIG. 12 turned from the metal layer 1100 can keep havingthe uniform thickness T2. Therefore, a thickness of the first section1102-1 and a thickness of the second section 1102-2 can be substantiallythe same. In other words, the first section 1102-1 and the secondsection 1102-2 can both have the thickness T2.

Continuing in FIG. 12 and referring to FIG. 13 at the same time, FIG. 13illustrates a cross-sectional view of the metal mask 1100 taken alongline B-B shown in FIG. 12 according to some other embodiments of thepresent disclosure. In some embodiments as shown in FIG. 13 , across-sectional structure of the metal mask 1100 may be similar to anupside-down-L-shaped structure. A third angle 83 is formed by the firstsection 1102-1 and the second section 1102-2. As discussed previously inFIG. 10 , an arrangement of the first insulation material 300 and thesecond insulation material 1000 on the conductive substrate 100 cantherefore determine a profile or design of the metal mask 1100. In someembodiments, a length D4 of the first section 1102-1 can substantiallybe the same as the width W1 of the conductive substrate 100 in FIG. 1 .

Referring to FIG. 14 to FIG. 17 , FIG. 14 to FIG. 17 are views ofvarious intermediate stages of applying the metal mask 1100 shown inFIG. 12 according to some other embodiments of the present disclosure.For example, the metal mask 1100 is used to form wires at the edge of aslab-shaped substrate. Various operations of embodiments are providedherein. The order in which some or all of the operations are describedshould not be construed to imply that these operations are necessarilyorder dependent. Alternative ordering will be appreciated having thebenefit of this description. Additional operations can be providedbefore, during, and/or after these operations in FIG. 14 to FIG. 17 ,and may be briefly described herein. Further, it will be understood thatnot all operations are necessarily present in each embodiment providedherein. Also, it will be understood that not all operations arenecessary in some embodiments.

FIG. 14 illustrates step A20 of receiving the slab-shaped substrate 700and disposing the metal mask 1100 at the edge of the slab-shapedsubstrate 700. In detail, the board portion 1104 of the metal mask 1100can directly contact the fifth surface S5 of the slab-shaped substrate700 which may be parallel to the xy plane. The strip-shaped structures1102 of the metal mask 1100 can directly contact the fifth surface S5 aswell as the seventh surface S7 which may be parallel to the yz plane.

The profile of the metal mask 1100 is designed to be consistent with aprofile of the slab-shaped substrate 700, thereby allowing the metalmask 1100 to fit the edge area of the slab-shaped substrate 700. In someembodiments, the width W2 of the slab-shaped substrate 700 cansubstantially be the same as the length D4 of the first section 1102-1of the strip-shaped structures 1102 (see FIG. 13 ). In some otherembodiments, the width W2 of the slab-shaped substrate 700 can be lessthan the length D4 of the first section 1102-1 of the strip-shapedstructures 1102 (see FIG. 13 ).

FIG. 15 illustrates step A22 of forming a first metal material 1500 onan exposed portion of the slab-shaped substrate 700 without the metalmask 1100 covered. In an embodiment as illustrated in FIG. 15 , thefirst metal material 1500 can be formed on the fifth surface S5 and theseventh surface S7. Specifically, the first metal material 1500 can beformed between each of the strip-shaped structures 1102. A thickness ofthe first metal material 1500 may be less than a thickness of the metalmask 1100 (e.g. the thickness T2 shown in FIG. 12 ). In someembodiments, a mask (not illustrated here) may be used to cover someother portions of the slab-shaped substrate 700 to avoid the first metalmaterial 1500 from appearing thereon. In some embodiments, the firstmetal material 1500 can be formed by a sputtering process, anevaporation process, or any suitable process. It is noted that, in anactual operation, the first metal material 1500 may be formed not onlyon the exposed portion of the slab-shaped substrate 700 but also on themetal mask 1100. For clarity, FIG. 15 is simplified by omitting toillustrate a portion of the first metal material 1500 on the metal mask1100.

FIG. 16 illustrates step A23 of inverting the metal mask 1100 in FIG. 15and then disposing the metal mask 1100 at the same edge of theslab-shaped substrate 700. In an embodiment as illustrated in FIG. 16 ,the board portion 1104 of the metal mask 1100 can directly contact thesixth surface S6 of the slab-shaped substrate 700. The strip-shapedstructures 1102 of the metal mask 1100 can directly contact the sixthsurface S6 as well as the seventh surface S7.

It is noted that, in step A23, a location on the seventh surface S7where the metal mask 1100 is disposed can be corresponding aligned witha location on the seventh surface S7 where the first metal material 1500is formed. In other words, that the first metal material 1500 and thestrip-shaped structures 1102 are alternately disposed on the seventhsurface S7 can be observed after the metal mask 1100 is disposed at thesame edge of the slab-shaped substrate 700.

Subsequently, a second metal material 1600 can be formed on an exposedportion of the slab-shaped substrate 700 without the metal mask 1100covered. In an embodiment as illustrated in FIG. 16 , the second metalmaterial 1600 can be formed on the sixth surface S6 and the seventhsurface S7. Specifically, the second metal material 1600 can be formedbetween each of the strip-shaped structures 1102. A thickness of thesecond metal material 1600 may be less than a thickness of the metalmask 1100 (e.g. the thickness T2 shown in FIG. 12 ). In someembodiments, a mask (not illustrated here) may be used to cover someother portions of the slab-shaped substrate 700 to avoid the secondmetal material 1600 from appearing thereon.

In some embodiments, the second metal material 1600 can be formed by asputtering process, an evaporation process, or any suitable process. Itis noted that, in an actual operation, the second metal material 1600may be formed not only on the exposed portion of the slab-shapedsubstrate 700 but also on the metal mask 1100. For clarity, FIG. 16 issimplified by omitting to illustrate a portion of the second metalmaterial 1600 on the metal mask 1100.

Further, since a metal material (e.g., the first metal material 1500 andthe second metal material 1600) is repeatedly formed on the seventhsurface S7 in step A22 and A23, the above-mentioned metal material canbe a double-layer stack including the first metal material 1500 and thesecond metal material 1600. In some embodiments, a thickness of theabove-mentioned double-layer stack may be less than a thickness of themetal mask 1100 (e.g. the thickness T2 shown in FIG. 12 ).

FIG. 17 illustrates step A24 of removing the metal mask 1100 such thatthe first metal material 1500 and the second metal material 1600 areremained and can collectively become metal wires 1700 at the edge of theslab-shaped substrate 700. The metal wires 1700 can extend on the fifthsurface S5, the sixth surface S6 and the seventh surface S7continuously. The metal wires 1700 can electrically connect variouselectrical components (not illustrated here) separately disposed on thefifth surface S5 and sixth surface S6. A thickness of the metal wires1700 on the seventh surface S7 may be greater than a thickness of themetal wires 1700 either on the fifth surface S5 or the sixth surface S6.In some embodiments, the thickness of the metal wires 1700 on theseventh surface S7 may be twice the thickness of the metal wires 1700 onthe fifth surface S5 or the sixth surface S6.

The present disclosure discloses various embodiments to provide a metalmask and a method of fabricating thereof. Thus, a metal mask with athree-dimensional structure can be formed through a more convenientprocess.

In addition, the metal mask with the three-dimensional structuredisclosed in the present disclosure can be made of metal. Due to a lowercoefficient of heat expansion of the metal than other materials (e.g.,polymer), the metal mask may be capable of a wide range of operationtemperature and better process reliability when the metal mask is usedin a process related to heating or change of temperature. Further, themetal mask with the three-dimensional structure disclosed in the presentdisclosure can fit an edge area of a slab-shape substrate. Then, by asputter process or an evaporation process through the metal mask, metalwires can be formed on three surfaces near the edge area of theslab-shape substrate to electrically connect various electricalcomponents separately disposed on two opposite sides of the slab-shapedsubstrate. Thus, using a metal mask during forming the metal wires nearthe edge area of the slab-shaped substrate can simplify fabricationprocess and reduce process cost.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentdisclosure without departing from the scope or spirit of the disclosure.In view of the foregoing, it is intended that the present disclosurecover modifications and variations of this disclosure provided they fallwithin the scope of the following claims.

What is claimed is:
 1. A method of fabricating a metal mask, comprising:receiving a conductive substrate, wherein the conductive substratecomprises: a first surface; a second surface, opposite to the firstsurface; a third surface, connecting the first surface and the secondsurface; a fourth surface, opposite to the third surface and connectingthe first surface and the second surface; forming a plurality oftrenches in a direction from the first surface to the second surface anda plurality of protrusions in the conductive substrate, wherein theplurality of trenches and the plurality of protrusions are alternatelyarranged; filling the plurality of trenches with a first insulationmaterial, wherein the first insulation material covers a first area ofthe plurality of protrusions; forming a metal layer on the conductivesubstrate, wherein the metal layer overlies a second area of theplurality of protrusions, and the second area is different from thefirst area; removing the first insulation material; and removing theconductive substrate such that the metal layer becomes a metal mask witha three-dimensional structure, wherein the metal mask with thethree-dimensional structure comprises a plurality of strip-shapedstructures.
 2. The method of fabricating the metal mask of claim 1,wherein the forming the metal layer on the conductive substratecomprises electrochemically depositing a material of the metal layer onthe conductive substrate.
 3. The method of fabricating the metal mask ofclaim 1, wherein the metal layer includes a first thickness between 20μm and about 300 μm.
 4. The method of fabricating the metal mask ofclaim 3, wherein the first thickness of the metal layer is a uniformthickness.
 5. The method of fabricating the metal mask of claim 3,wherein the metal mask includes a second thickness and the secondthickness is substantially the same as the first thickness.
 6. Themethod of fabricating the metal mask of claim 1, wherein the forming themetal layer on the conductive substrate comprises forming the metallayer on the first surface and the third surface.
 7. The method offabricating the metal mask of claim 6, further comprising forming asecond insulation material on the fourth surface.
 8. The method offabricating the metal mask of claim 7, further comprising removing thesecond insulation material after the forming the metal layer on theconductive substrate.
 9. The method of fabricating the metal mask ofclaim 7, wherein a material of the second insulation material issubstantially the same as a material of the first insulation material.10. The method of fabricating the metal mask of claim 6, wherein theforming the metal layer on the conductive substrate further comprisesforming the metal layer on the fourth surface.
 11. The method offabricating the metal mask of claim 1, wherein a length of the pluralityof trenches is substantially the same as a distance between the thirdsurface and the fourth surface.
 12. The method of fabricating the metalmask of claim 1, wherein the forming the plurality of trenches in adirection from the first surface to the second surface and a pluralityof protrusions in the conductive substrate comprises machining theconductive substrate to recess the first surface of the conductivesubstrate.
 13. The method of fabricating the metal mask of claim 1,wherein the plurality of strip-shaped structures is a portion of themetal layer overlying the protrusions.
 14. A metal mask, comprising: afirst board portion; and a plurality of strip-shaped structuresconnected to the first board portion, wherein two adjacent strip-shapedstructures of the plurality of strip-shaped structures are spaced apartfrom each other, and wherein the plurality of strip-shaped structurescomprise: a first section having a first thickness; and a second sectionhaving a second thickness substantially the same as the first thickness,wherein the second section connects the first board portion and thefirst section, and a first angle is formed by the first section and thesecond section.
 15. The metal mask of claim 14, wherein the plurality ofstrip-shaped structures further comprises a third section connected tothe first section such that a second angle is formed by the firstsection and the third section.
 16. The metal mask of claim 15, whereinthe third section has a third thickness substantially the same as thefirst thickness and the second thickness.
 17. The metal mask of claim15, wherein the second section and the third section are parallel toeach other.
 18. The metal mask of claim 15, further comprising a secondboard portion, wherein the third section connects the second boardportion and the first section.
 19. The metal mask of claim 18, whereinthe first board portion and the second board portion are parallel toeach other.